// Copyright Epic Games, Inc. All Rights Reserved.

#include "CoreMinimal.h"
#include "Stats/Stats.h"
#include "TickableEditorObject.h"
#include "DistanceFieldAtlas.h"
#include "Framework/Notifications/NotificationManager.h"
#include "Widgets/Notifications/SNotificationList.h"
#include "Templates/UniquePtr.h"

/** Notification class for asynchronous distance field building. */
class FDistanceFieldBuildNotificationImpl
    : public FTickableEditorObject
{

public:
    FDistanceFieldBuildNotificationImpl()
    {
        LastEnableTime = 0;
    }

    /** Starts the notification. */
    void DistanceFieldBuildStarted();

    /** Ends the notification. */
    void DistanceFieldBuildFinished();

protected:
    /** FTickableEditorObject interface */
    virtual void Tick(float DeltaTime) override;
    virtual ETickableTickType GetTickableTickType() const override
    {
        return ETickableTickType::Always;
    }
    virtual TStatId GetStatId() const override;

private:
    /** Tracks the last time the notification was started, used to avoid spamming. */
    double LastEnableTime;

    /** In progress message */
    TWeakPtr<SNotificationItem> DistanceFieldNotificationPtr;
};

/** Global notification object. */
TUniquePtr<FDistanceFieldBuildNotificationImpl> GDistanceFieldBuildNotification;

void SetupDistanceFieldBuildNotification()
{
    // Create explicitly to avoid relying on static initialization order
    GDistanceFieldBuildNotification = MakeUnique<FDistanceFieldBuildNotificationImpl>();
}

void TearDownDistanceFieldBuildNotification()
{
    GDistanceFieldBuildNotification = nullptr;
}

void FDistanceFieldBuildNotificationImpl::DistanceFieldBuildStarted()
{
    LastEnableTime = FPlatformTime::Seconds();

    // Starting a new request! Notify the UI.
    if (DistanceFieldNotificationPtr.IsValid())
    {
        DistanceFieldNotificationPtr.Pin()->ExpireAndFadeout();
    }

    FNotificationInfo Info(NSLOCTEXT("DistanceFieldBuild", "DistanceFieldBuildInProgress", "Building Mesh Distance Fields"));
    Info.bFireAndForget = false;

    // Setting fade out and expire time to 0 as the expire message is currently very obnoxious
    Info.FadeOutDuration         = 0.0f;
    Info.ExpireDuration          = 0.0f;

    DistanceFieldNotificationPtr = FSlateNotificationManager::Get().AddNotification(Info);

    if (DistanceFieldNotificationPtr.IsValid())
    {
        DistanceFieldNotificationPtr.Pin()->SetCompletionState(SNotificationItem::CS_Pending);
    }
}

void FDistanceFieldBuildNotificationImpl::DistanceFieldBuildFinished()
{
    // Finished all requests! Notify the UI.
    TSharedPtr<SNotificationItem> NotificationItem = DistanceFieldNotificationPtr.Pin();

    if (NotificationItem.IsValid())
    {
        NotificationItem->SetText(NSLOCTEXT("DistanceFieldBuild", "DistanceFieldBuildFinished", "Finished building Distance Fields!"));
        NotificationItem->SetCompletionState(SNotificationItem::CS_Success);
        NotificationItem->ExpireAndFadeout();

        DistanceFieldNotificationPtr.Reset();
    }
}

void FDistanceFieldBuildNotificationImpl::Tick(float DeltaTime)
{
    if (GDistanceFieldAsyncQueue)
    {
        // Trigger a new notification if we are doing an async build, and we haven't displayed the notification recently
        if (GDistanceFieldAsyncQueue->GetNumOutstandingTasks() > 0 && !DistanceFieldNotificationPtr.IsValid() && (FPlatformTime::Seconds() - LastEnableTime) > 5)
        {
            DistanceFieldBuildStarted();
        }
        // Disable the notification when we are no longer doing an async compile
        else if (GDistanceFieldAsyncQueue->GetNumOutstandingTasks() == 0 && DistanceFieldNotificationPtr.IsValid())
        {
            DistanceFieldBuildFinished();
        }
        else if (GDistanceFieldAsyncQueue->GetNumOutstandingTasks() > 0 && DistanceFieldNotificationPtr.IsValid())
        {
            TSharedPtr<SNotificationItem> NotificationItem = DistanceFieldNotificationPtr.Pin();

            if (NotificationItem.IsValid())
            {
                FFormatNamedArguments Args;
                Args.Add(TEXT("BuildTasks"), FText::AsNumber(GDistanceFieldAsyncQueue->GetNumOutstandingTasks()));
                FText ProgressMessage = FText::Format(NSLOCTEXT("DistanceFieldBuild", "DistanceFieldBuildInProgressFormat", "Building Mesh Distance Fields ({BuildTasks})"), Args);

                NotificationItem->SetText(ProgressMessage);
            }
        }
    }
}

TStatId FDistanceFieldBuildNotificationImpl::GetStatId() const
{
    RETURN_QUICK_DECLARE_CYCLE_STAT(FDistanceFieldBuildNotificationImpl, STATGROUP_Tickables);
}